318 



TROCHID^. 



and when at rest showing on each side similar lines of dif- 

 ferent lengths, which are rather less numerous and more irre- 

 gularly disposed towards the tail ; these lateral lines represent 

 folds or creases that disappear when the foot is in action : 

 appendages 3 on each side (sometimes 4 on one side and 3 

 on the other, Clark), tapering, ringed and setose, like the 

 tentacles ; there is frequently at the base of each appendage 

 a white or yellow tubercle on either side of it. 



Shell regularly conical, very thick, opaque, and of a dull 

 hue : sculpture, none in the adult ; but the young have spiral 

 ridges and minute cross striae, as in T. cinerarius and other 

 species of the same section : colour yellowish or light-grey, 

 with a greenish tinge, variegated by numerous and close-set 

 zigzag purplish markings, arranged in longitudinal rows or 

 streaks, giving the surface an obscurely tessellated appearance ; 

 apex (which is always eroded) of a yellowish hue, and some- 

 times partly exposing the inner layer of nacre : spire more or 1 

 less raised, and bluntly pointed : whorls 6, rather quickly 

 enlarging, and convex ; the upper part of the last whorl is 

 compressed or somewhat flattened : suture slight: mo utli large, 

 obliquely oval: outer lip rounded, and sharp-edged, with a 

 slight notch or angular point at the upper corner : inner lip 

 extremely thick and broad, reflected a little over the umbilicus ; 

 it is furnished below the middle with a remarkably strong 

 tubercular prominence, which is nacreous and apparent in all 

 states of growth : inside beautifully iridescent, except at the 

 margin, the outer zone of which is mottled with black and 

 green, and is microscopically pustulated, and the inner is white 

 and almost pearly : umbilicus rather large but shallow, partly 

 covered by the inner lip ; the base of the shell is more or less 

 worn away by the continual friction of the upper part of the 

 foot : operculum yellowish-horncolour, with about 15 volutions, 

 each of which is obliquely and minutely striated in the line 

 of growth. L. nearly 1. B. 1. 



Var. minor. Smaller, and eroded. 



Habitat : Local, but not uncommon, on rocks and 

 stones just below high- water mark at neap tides in the 

 counties of Dorset, Devon, and Cornwall; Channel 

 Isles (Hanley) ; bays near Swansea (J. G. J.) ; Pwll- 

 heli, Carnarvonshire (Da Costa) ; Anglesea (Donovan) ; 

 Ireland, as far north as Donegal Bay (Waller and 



